Erika laughed even more at David when he made his statement about not eating brains and how he is a knight. She laughed "Oh. My. God! You think you're a knight? Well, you're in the wrong time dude!" Erika laughed even more when he spoke to the professor. Joan sighed and shook her head. 
When he obeyed May, Erika asked "May, why is he listening to you?" 
May shrugged and answered "I have no idea honestly,"

The Professor then cleared his throat and he asked May, "Well, are you three done with your assignment?" 
May sighed "Yes," as she handed him the worksheet. The professor scrutinized it carefully, before he conceded "Alright, you and your…friends, can go," 
May thanked him, and she said to the other three "Let's get out of here," 
Erika joked "Yeah, wouldn't want you and your heavy weight to fall through the ground again,"
May answered sarcastically "Har. Har,"